[antz123]

@warrior1975
 
Thank you, Yes as awesome it feels and I might say Stacking doesnt matter, practicality and portability of the same on a daily basis might be a big pain. I wont deny what you said. Just the world of DAP is equally confusing. , dont think I can buy new device every other year, thus want to be future proof.

 

[Mojo ideas]

Wait, what? There's a player add-on coming? I remember seeing something like that being talked about like half a year ago but I thought it wasn't going to be a real product.

Let's just say that I think if we've got this right the new product will put a small bulge in your pocket

 

[Bengkia369]

Let's just say that I think if we've got this right the new product will put a small bulge in your pocket

Sounds like a big hint something great is coming out - a Mojo DAP module!

 

[Delayeed]

Let's just say that I think if we've got this right the new product will put a small bulge in your pocket

Oh gosh I'm already starting to feel it 

 

[ThomasHK]

Let's just say that I think if we've got this right the new product will put a small bulge in your pocket

Please have streaming... Please have streaming... Please have streaming...

 

[Rob Watts]

 

  If I were to use rounding then what you say is correct, there would be small signal non-linearity.
 
But Mojo categorically does not use anything as crude as rounding to convert bit depths as the volume function is running at 16FS (705.6 kHz or 768 kHz) - I use extensive noise shaping to change bit depths. Mojo's noise shaping from beginning to end through all the intermediate paths (that is digital input to the 4e pulse array outputs) ensures 200 dB performance in band - that's better than 32 bit performance. The benefit of this is small signal non-linearity is much better, and this is essential for depth perception - the tiniest error in small signal amplitude, no matter how small, is audible in terms of truncation of perceived depth of sound-stage.
 
Your assertion that analogue does not have these problems is incorrect. Any metal to metal interface contains oxides and other impurities - and copper oxide is diodic, and so attenuates small signals and creates small signal distortion. Moreover, carbon track volume controls are also non linear, as carbon composition has significant voltage dependency of resistance - another source of non-linearity. Analogue electronics additionally suffer from RF noise pick-up, which when added to an active stage will then create more noise floor modulation due to audio signal and random RF noise inter-modulation.
 
Mojo, unlike all other non Chord DAC's, has no measurable noise floor modulation, and zero distortion of small signals, with no measurable fundamental signal non-linearity. This is not something that other DAC's can do, nor is it something that an analogue volume control can do too. And the benefit of all this is refinement and transparency - key ingredients for musicality.
 
Rob 

I love how you take the time to come in here and correct false assumptions. Really learning a lot from all your input. Your piece on subjective testing was very informative and I'm sure I'll use parts of it in my day job (headphones engineer).
 
On several occassions I've seen you mention that small signal modulation or non-linearity is introduced due to injected noise. Does this show up on IMD measurements, THD for very small level test signals, both or do you have to assess this somehow else?

 
Sure, noise floor modulation is easy to measure with the right test equipment (test equipment has its own noise floor modulation too). Simply run it with no signal, measure the noise floor, run the output at say 2.5v and you will see the noise floor rise using an FFT.
 
So here is the noise floor modulation for Mojo:
 

 
So red is no signal, blue is with 2.5v RMS. Why do I use 2.5v RMS? Because if it is higher than 2.5v the APX555 test equipment will give poorer measured performance. Mojo's performance is actually a challenge for most test gear, and you need state of the art measuring equipment to get accurate results. Now with normal DAC's, the noise floor will rise with the signal itself, so instead of it being constant at -175dB, it will rise to say -150dB.
 
Unfortunately the ear/brain is very sensitive to this issue - noise floor modulation makes things sound bright, hard and aggressive. But actually we can hear levels well below the measuring limits of the best test gear; I have had digital FFT's with noise floor of -200 dB modulating to -190dB - something you would never be able to measure as it would be swamped by analogue noise - but removing the noise floor modulation results in the SQ becoming warmer and smoother.
 
Rob 

 

[STR-1]

I don't know how long the offer has been on their website but I see http://www.audiosanctuary.co.uk are giving a free Mojo case with every Mojo ordered.

 

[ThomasHK]

Sure, noise floor modulation is easy to measure with the right test equipment (test equipment has its own noise floor modulation too). Simply run it with no signal, measure the noise floor, run the output at say 2.5v and you will see the noise floor rise using an FFT.

So here is the noise floor modulation for Mojo:




So red is no signal, blue is with 2.5v RMS. Why do I use 2.5v RMS? Because if it is higher than 2.5v the APX555 test equipment will give poorer measured performance. Mojo's performance is actually a challenge for most test gear, and you need state of the art measuring equipment to get accurate results. Now with normal DAC's, the noise floor will rise with the signal itself, so instead of it being constant at -175dB, it will rise to say -150dB.

Unfortunately the ear/brain is very sensitive to this issue - noise floor modulation makes things sound bright, hard and aggressive. But actually we can hear levels well below the measuring limits of the best test gear; I have had digital FFT's with noise floor of -200 dB modulating to -190dB - something you would never be able to measure as it would be swamped by analogue noise - but removing the noise floor modulation results in the SQ becoming warmer and smoother.

Rob 

Apologies if this is a stupid question but how do you distinguish this from harmonic distortion? The peaks seen in the fft are all harmonically related to the test signal. Is it because of the magnitude of the harmonics not going down as a function of frequency or are there harmonics below the fundamental that would indicate modulation?

 

[Mimouille]

Hey if anyone needs a stack to pair with the Mojo, check my signature, I have the AK100 mk2 plus sysconcept.

 

[willowbrook]

So I want to charge and play at the same time without using battery like a desktop dac/amp. I do not want to use the battery and let the mojo draw current only from the power supply. Does it matter if I plug the power source before turning it on or plugging it in after turning it on?

 

[GreenBow]

 

Let's just say that I think if we've got this right the new product will put a small bulge in your pocket

Please have streaming... Please have streaming... Please have streaming...

 
Please have another model without streaming, so we that don't stream need not pay for streaming('s) implementation. Please!

 

[435279]

  Hi Guys... I'm looking for your experiences and prevailing wisdom for making a Mojo a remotely-located Roon-capable endpoint. So here's what's on my mind. We know from Rob and our experience that the Mojo is quite good at protecting SQ from jitter. Yet, I think it fair to say it isn't immune to it either. Also, we know that the Mojo likes being fed optically, as it eliminates a source of RF modulation. So, specifically in the context of using a Mojo, what is the smart move when balancing sound quality versus cost, in the following scenarios. Or are the rave reviews everywhere for the MicroRendu simply a dominating reality (even with the Mojo), nothing else is really even close, so just start saving mass quantities of money?
 
One - Sonore SonicOrbiter SE - Feeding Mojo Optically
Two - Sonore SonicOrbiter SE - Feeding Mojo via USB
Three - Sonore MicroRendu - Feeding via USB
Four - HifiBerry with Raspberry Pi - Feeding Optically
Five - HifiBerry with Raspberry Pi - Feeding Coax S/Pdif

 
I do option 4 all the time, sounds great to me and a lot cheaper than the Sonore options.
 
I'm using DietPi on the Raspberry Pi.

 

[Mython]

  So I want to charge and play at the same time without using battery like a desktop dac/amp. I do not want to use the battery and let the mojo draw current only from the power supply. Does it matter if I plug the power source before turning it on or plugging it in after turning it on?

 
 
You cannot completely avoid using Mojos battery. As John Franks has remarked, there is a slight net drain on the battery, even whilst plugged-in.
 
 
Please see the discussion in the section of post #3, entitled  'Battery & Charging'  /  'What happens when you charge & listen at the same time?'
 
 
Also, Rob has been good enough to provide me with additional detail on this matter, today (which I am also adding to the above section in post #3, but will share here):
 
 

Originally Posted by Rob Watts

 
the battery is always connected - but - when the charger is on, and the battery is fully charged, then the trickle charge is balanced by the current that the amp needs, so no nett charge going into the battery - its just going from the charger to the amp... The battery is still providing a low impedance, and dynamic surge currents though, but the average DC current is just matched by the charger.
 
Rob 

 
 
Thanks for clarifying, Rob.

 

[Mython]

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I am sure that this has been asked before.
Does it do any damage if one inadvertently puts power into the micro USB port?

 
 
Quote:

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/img/forum/go_quote.gif

Lol, I don't think I damaged mine when I did that long ago.

 

/img/forum/go_quote.gif

Don't think it should as the data port also does a voltage "check" (if I recall correctly, it was mentioned before), thus should be safe.

Thanks guys.I was expecting to be firmly directed to post 3! I didn't know what to search though!

 
Thanks guys.I was expecting to be firmly directed to post 3! I didn't know what to search though!

Search using the keyword VBUS. Only people who have a suspicion of the correct answer already, are likely to use that term.

 
 
Just to follow-up on this, I asked Rob and he's confirmed, which I've now added to post #3 under 'Battery & Charging' \ 'Does it do any damage if one inadvertently puts power into the microUSB data port?'

 

[willowbrook]

   
 
You cannot completely avoid using Mojos battery. As John Franks has remarked, there is a slight net drain on the battery, even whilst plugged-in.
 
 
Please see the discussion in the section of post #3, entitled  'Battery & Charging'  /  'What happens when you charge & listen at the same time?'
 
 
It was also recently reiterated here: www.head-fi.org/t/784602/chord-mojo-dac-amp-faq-in-3rd-post/25650#post_13005155
 
 
As I understand it, there is no direct route from the charger to the DAC-amp circuitry. The charger connects to the charging circuit, which connects to the battery, and the DAC-amp circuitry draws power from the battery. I will check with Rob Watts, to confirm this, and update this post afterwards.
 
 
.

Thanks, so basically turn the mojo on and then plug in = trickle charge mode = no timer. To reset the timer, plug it again. I guess it's just like a phone using battery as main source while charger charges the battery constantly. I don't know if draining battery completely-->charging or trickle charging is better.